Insulating varnish and insulation laminate

ABSTRACT

An insulation laminate is disclosed having a base laminate layer, with at least one flat side coated with a layer of an insulating varnish, the insulating varnish including a basecoat; and an added lubricant.

RELATED APPLICATIONS

This application claims priority as a continuation application under 35U.S.C. § 120 to PCT/EP2012/001501, which was filed as an InternationalApplication on Apr. 4, 2012 designating the U.S., and which claimspriority to European Application 11003554.0 filed in Europe on May 2,2011. The entire contents of these applications are hereby incorporatedby reference in their entireties.

FIELD

The present disclosure relates to an insulating varnish and aninsulation laminate that has a base laminate layer.

BACKGROUND INFORMATION

It is known that rotating electrical machines or generators can have atleast one basic element produced from a laminated core, such as forexample a stator, in which a magnetic flux occurring during theoperation of this component is guided. Laminated cores are used here forthe construction to for example avoid, or at least reduce, eddycurrents.

The electrical winding conductors for such components, for example astator winding, can be guided in winding slots, which are formed aschannel-like clearances through respective laminated cores. The windingslots can be lined on their boundary surfaces with a sheet-likeinsulating material, so that the electrical insulation between thewinding and the laminated core is increased. Single- or multi-plyflexible insulating sheetings (IEC 60626-3) are used as insulatingmaterials. These flexible insulating materials may be additionally usedwith coatings for adhesive bonding to the laminated core or withcoatings for increasing the aging resistance (IEC 60626-3 Sheet 502ff)at elevated temperature.

In the production of such machines or generators, therefore, therespective laminated core or further components first have to beproduced, then the respective winding conductor is pulled into theslots. Especially in the case of smaller machines, for example in thecase of motors in the power range from <1 kW to 10 kW and above, when itis introduced into the respective winding slots a winding conductor isat least partially pulled through them.

However, known insulating sheetings described in the standard have amaterial-dependent surface roughness, which in the case of automatedprocessing represents a factor limiting the production rate. In the caseof automated production, the slot cell can be first insulated and thenthe winding is pulled in together with a slot seal. As this happens, onthe one hand the winding rubs against the slot cell insulation and onthe other hand the slot cell insulation rubs against the slot seal.Depending on the COF (Coefficient of Friction) of the elementsundergoing friction, damage to the insulation may occur, or the pullingin of the insulation is prevented.

SUMMARY

An insulation laminate is disclosed having a base laminate layer, withat least one flat side coated with a layer of an insulating varnish, theinsulating varnish comprising: a basecoat; and an added lubricant.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary advantages of features disclosed herein will be explained inconnection with the insulation laminate disclosed herein.

Further embodiments and further advantages are to be described in moredetail on the basis of exemplary embodiments that are represented in thedrawings, in which:

FIG. 1 shows a section through an exemplary insulation laminate; and

FIG. 2 shows exemplary working steps A, B, C when introducing a windingconductor.

DETAILED DESCRIPTION

An insulating sheeting or materials therefor are disclosed by which thepreviously described friction effects can be reduced.

For example, an insulating varnish of the type already mentioned isdisclosed which is characterized by a main basecoat component and anadded lubricant. For example, insulating sheetings are coated at leaston one side, or on both sides with a basecoat, which serves forimproving the aging resistance. However, this basecoat can alsocontribute to a considerable extent to the frictional characteristicsalong the surface of the insulating sheeting. As disclosed herein,adding a lubricant to the basecoat produces an insulating varnish, whichafter being applied to the insulating sheeting and cured, can improvefrictional characteristics, for example on account of being given theform of a two-component varnish.

According to an exemplary embodiment of an insulating varnish disclosedherein, the basecoat is a polyester-imide or epoxy varnish. As disclosedherein, such varnishes have proven successful for the coating ofinsulating sheetings even without any added material, though withfrictional behavior that could be improved. Such varnishes are forexample made up as a 2-component material, using for example a stockvarnish and a hardener, which are mixed together shortly before beingapplied and then cured.

According to a further exemplary embodiment of an insulating varnishdisclosed herein, an amide wax dispersion is used as the added lubricantin a proportion by weight of 2% to 25% of the insulating varnish, withfor example a lower range from 2% to 10% being preferred. This is sobecause it has been found that even relatively small amounts of theaddition can be sufficient for achieving desired effects disclosedherein. For example, the basecoat and the added lubricant make up 100%.

The present disclosure is also directed to an insulation laminate thathas a base laminate layer which is coated at least on one of its flatsides with a layer of an insulating varnish as disclosed herein. Thisvarnish is for example ideally cured, because this can bring out bestthe frictional properties of the surface of the insulation laminate.

This is so because the lubricant disclosed herein can include an amidewax dispersion, having a property that at room temperature itaccumulates on the surface of the dried insulating varnish layer and attemperatures greater than 60° C. it migrates away from the surface, thatis to say withdraws into the interior of the dried insulating varnishlayer. On the one hand, this can have an advantage that, when a windingconductor is introduced into the winding slots that are lined with aninsulation laminate as disclosed herein, an extremely smooth surface isprovided, which is conducive to sliding when the winding conductor ispulled in. This is so because, according to exemplary embodimentsdisclosed herein, the introduction of winding conductors is performed atroom temperature, that is to say for example in a temperature range ofapproximately 15° C. to 30° C., preferably such as at about 20° C.

On the other hand, however, such a sliding layer can be disadvantageousfor an encapsulation of the pulled-in winding conductor which is forexample to be carried out thereafter, if this is likewise performed atroom temperature. Encapsulation is intended to finally stabilize thewinding or the winding conductor, in order to achieve a high degree ofrobustness of the end product, for example of the motor. Such a slidinglayer would therefore be counter to the aim of an encapsulation, becausea bonding of the encapsulating compound to the winding conductor wouldbe considerably reduced.

However, such an encapsulation is not for example performed under roomtemperature conditions, but either with a hot encapsulating compound orwhile the component concerned is heated to a drying temperature of theencapsulating compound, for example 110° C. In this case, thetemperature causes the sliding layer to migrate into the interior of thevarnish layer and the encapsulating compound can enter into a connectionactuated by adherence with the winding or the winding conductor duringthe curing of the compound. This can for example advantageously ensurestabilization of the winding by the encapsulating compound.

If an encapsulating compound that does not require an elevatedtemperature during processing or for curing is chosen, it should then becorrespondingly heated. This can either be performed directly, or can beperformed indirectly by heating the winding, for example also bytemporarily applying a short-circuiting current to the electricallyoperational winding.

It has been found that an average thickness of the insulating varnishlayer in an exemplary range from 2 μm to 15 μm proves to be particularlyfavorable with respect to the sliding and/or insulating propertiesthereby achieved. In relation to this, exemplary layer thicknesses of abase laminate layer lie in an exemplary range from 90 μm to 800 μm. Thelower layer thickness range of the base laminate layer can be limited byan inadequate mechanical stability of the insulation laminate, and theupper layer thickness range can be limited by an inadequate mechanicalflexibility of the insulation laminate, no longer allowing it to beunproblematically laid in a winding slot.

According to further exemplary embodiments, the following baselaminates, which have already been used for a comparable purpose withoutthe added lubricant disclosed herein have proven to be particularlysuitable for being used as a base laminate material for an insulationlaminate as disclosed herein:

-   -   pressboard/PET film laminate,    -   PET film/PET nonwoven laminate,    -   NOMEX/PET film laminate,    -   NOMEX/polyimide film laminate.

NOMEX is a name for aramid paper that is familiar to those skilled inthe art. Such laminates are for example multi-layered and symmetrical interms of the layer structure, for example with 2 or 3 or more layers. Inthe case of the aforementioned combinations, there is inter aliaparticularly good bonding of the insulating varnish disclosed herein tothe surface of the base laminate. It should be mentioned in thisconnection that the base varnish material is, for example, a 2-componentmaterial, so that a lower temperature is used for its curing and thesliding layer accumulates on the surface of the varnish layer during thedrying phase of the insulating varnish as disclosed herein.

Methods for introducing a winding into at least one winding slot of astator or rotor are also disclosed and can include:

-   -   lining the at least one winding slot with an insulation laminate        as disclosed herein    -   pulling a winding conductor into the at least one winding slot        under room temperature conditions    -   encapsulating the winding conductor in the at least one winding        slot at an elevated temperature.

FIG. 1 shows a section 10 through an exemplary insulation laminate 12 asdisclosed herein, which includes a three-layered base laminate 14 and acoating on both sides with an insulating varnish layer 16, 17 with addedlubricant. The layer thicknesses of the insulating varnish layers 16, 17are in this case each for example approximately 5 μm. The base laminatecan include a middle laminate layer 20 with a layer thickness ofapproximately 200 μm having a PET nonwoven laminate. The two outerlaminate layers 18, 22 are produced from a PET nonwoven and have anexemplary layer thickness of 50 μm each.

FIG. 2 shows exemplary working steps A, B, C when introducing a windingconductor into a winding slot in an elevation 30. The first illustration30A shows a winding slot 32, which has been let into a laminated core ofa stator of a motor, as indicated by its boundary surfaces 34. Dependingon the size and power of the motor, the depth of the winding slot is,for example, 1 cm to 3 cm, for motors of a relatively small size, forexample for power drills or vacuum cleaners. The width of the slot lies,for example, in a range from 0.5 cm to 6 cm. However, it goes withoutsaying that significantly larger motors or generators, withcorrespondingly different slot dimensions, are also possible andenvisaged

The illustration 30B illustrates a folded insulation laminate 36 asdisclosed herein which has a thickness of for example approximately 200μm and has been placed in the winding slot. In the case of the low motorpower, and consequently also motor voltage, assumed in this example,this is absolutely sufficient for the electrical insulation of anassumed exemplary maximum 1 kV.

The illustration 30C additionally indicates a placed-in winding wire 38,the conductor cross section absolutely not being to scale; rather, amuch greater number of windings of the winding conductor 38, with acorrespondingly smaller cross section, should be expected. The windingformed by the winding conductor 38 extends at least also over a furtherwinding slot that lies symmetrically opposite and is not shown. Thewinding slot or the slot cell can be covered with a slot seal 40,likewise having an insulation laminate as disclosed herein, but this hasa slightly increased layer thickness for mechanical reasons. It can beassumed that the winding is encapsulated in exemplary embodiments, sothat the slot cell with the winding conductor 38 arranged therein isfilled with an encapsulating compound (not represented), by which thewinding is secured.

It will be appreciated by those skilled in the art that the presentinvention can be embodied in other specific forms without departing fromthe spirit or essential characteristics thereof. The presently disclosedembodiments are therefore considered in all respects to be illustrativeand not restricted. The scope of the invention is indicated by theappended claims rather than the foregoing description and all changesthat come within the meaning and range and equivalence thereof areintended to be embraced therein.

LIST OF DESIGNATIONS

-   10 section through an exemplary insulation laminate-   12 insulation laminate-   14 base laminate layer-   16 first insulating varnish layer-   17 second insulating varnish layer-   18 first layer of the base laminate-   20 second layer of the base laminate-   22 third layer of the base laminate-   30 working steps A, B, C when introducing a winding conductor-   32 interior space of an exemplary winding slot-   34 boundary surface of an exemplary winding slot-   36 insulation laminate-   38 winding conductor-   40 slot seal

The invention claimed is:
 1. A folded insulation laminate comprising: a base laminate comprising pressboard and having at least one side coated with a layer of an insulating varnish, the insulating varnish comprising a basecoat and an added lubricant; wherein the basecoat is a polyester-imide or epoxy varnish, the added lubricant is an amide wax dispersion in a proportion by weight of 2% to 25%, the insulating varnish is cured, and an average thickness of the insulating varnish layer lies in a range from 2 μm to 15 μm; and wherein the folded insulation laminate includes a number of sections shaped complimentary to boundary surfaces of a winding slot of a motor to define a receptacle having an open outer side to receive a winding.
 2. The folded insulation laminate as claimed in claim 1, the base laminate further comprising PET film.
 3. The folded insulation laminate as claimed in claim 1, wherein the number of sections includes a first section shaped to correspond with a first of the boundary surfaces of the winding slot, a second section shaped to correspond with a second of the boundary surfaces of the winding slot, and a fold defined between the first and second sections.
 4. The folded insulation laminate as claimed in claim 3, wherein the first section of the folded insulation laminate is angled relative to the second section.
 5. The folded insulation laminate as claimed in claim 4, wherein the number of sections includes a third section shaped to correspond with a third of the boundary surfaces of the winding slot and another fold defined between the second and third sections.
 6. The folded insulation laminate as claimed in claim 5, wherein the third section of the folded insulation laminate is angled relative to the second section.
 7. An assembly of insulation laminate comprising: a folded insulation laminate as claimed in claim 1, and a slot seal arranged complimentary with the number of sections to extend across the receptacle at the open outer side to cover the receptacle.
 8. The assembly as claimed in claim 7, wherein the slot seal includes a seal laminate layer with at least one side coated with a layer of the insulating varnish.
 9. The assembly as claimed in claim 8, wherein the layer of the insulating varnish on the at least one side of the seal laminate layer is thicker than the at least one layer of insulating varnish on the base laminate.
 10. The folded insulation laminate as claimed in claim 1, wherein the base laminate includes a second side, opposite the at least one side, the second side being coated with the insulating varnish.
 11. The folded insulation laminate as claimed in claim 2, wherein the base laminate includes a middle layer comprising the pressboard and a first outer layer comprising PET film.
 12. The folded insulation laminate as claimed in claim 11, wherein the base laminate includes a second outer layer comprising PET film arranged opposite the first outer layer.
 13. The folded insulation laminate as claimed in claim 12, wherein the first outer layer forms the at least one side coated with the layer of the insulating varnish, and the second outer layer forms another side coated with a layer of the insulating varnish.
 14. The folded insulation laminate as claimed in claim 1, wherein an average thickness of the base laminate lies in a range from 80 μm to 1000 μm.
 15. The folded insulation laminate as claimed in claim 1, wherein the base laminate includes an opposite side coated with a layer of the insulating varnish.
 16. A winding slot of a motor comprising: a folded insulation laminate having a number of sections shaped complimentary to boundary surfaces of the winding slot to define a receptacle having an open outer side to receive a winding, the folded insulation laminate comprising a base laminate comprising pressboard, the base laminate having at least one side coated with a layer of insulating varnish, the insulating varnish comprising: a basecoat including a polyester-imide or epoxy varnish; and an added lubricant including an amide wax dispersion in a proportion by weight of 2% to 25%; wherein the insulating varnish is cured and an average thickness of the insulating varnish layer lies in a range from 2 μm to 15 μm.
 17. A motor comprising: a winding slot including a winding of the motor received therein; and a folded insulation laminate having a number of sections shaped complimentary to boundary surfaces of the winding slot, the folded insulation laminate comprising a base laminate comprising pressboard, the base laminate having at least one side coated with a layer of insulating varnish, the insulating varnish comprising: a basecoat including a polyester-imide or epoxy varnish; and an added lubricant including an amide wax dispersion in a proportion by weight of greater than 20% up to 25%; wherein the insulating varnish is cured and an average thickness of the insulating varnish layer lies in a range from 2 μm to 15 μm.
 18. The folded insulation laminate as claimed in claim 5, wherein the first and third sections each include (i) a free end and (ii) an opposite end connected with second section, the free ends of the first and third sections defining the open outer side of the receptacle therebetween.
 19. The assembly as claimed in claim 7, wherein the slot seal includes a seal laminate layer with at least one side coated with a layer of the insulating varnish.
 20. The assembly as claimed in claim 19, wherein the layer of the insulating varnish on the at least one side of the seal laminate layer is thicker than the at least one layer of insulating varnish on the base laminate. 